How to Calculate Your Monthly Mortgage Payment
Understand exactly what makes up a mortgage payment — principal, interest, taxes, insurance, and PMI — and how to estimate yours before you ever talk to a lender.
The four parts of a mortgage payment (PITI)
- Principal — the portion that pays down what you borrowed.
- Interest — the lender's charge for the loan, highest in the early years.
- Taxes — property taxes, usually collected monthly into an escrow account.
- Insurance — homeowner's insurance, plus PMI if your down payment is under 20%.
The formula behind principal and interest
Monthly P&I = P × [r(1+r)ⁿ] ÷ [(1+r)ⁿ − 1], where P is the loan amount, r is the monthly interest rate (annual rate ÷ 12), and n is the number of payments (years × 12).
On a $320,000 loan at 7% over 30 years, that works out to about $2,129/month in principal and interest — before taxes and insurance are added.
Why a small rate change matters so much
Because interest compounds over decades, even a 1% rate difference can change your payment by hundreds of dollars a month and tens of thousands over the life of the loan. This is why shopping multiple lenders and improving your credit score pays off so heavily.
Estimate yours instantly
Our Mortgage Calculator does this full PITI math and shows you a complete amortization schedule. Pair it with the Home Affordability Calculator to find a comfortable price range first.
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Mortgage Calculator
Calculate monthly mortgage payments, total interest, and view a full amortization schedule.
Home Affordability Calculator
Find out how much house you can afford based on income and expenses.
Loan Calculator
Calculate monthly payments and total interest for any personal or auto loan.
Property Tax Calculator
Estimate annual property taxes based on home value and local tax rates.